Thirteen herbicide treatments were applied on May 8, 2006, on a golf course fairway to assess transition and turf quality effects. Initial injury to perennial ryegrass was most extreme for Tranxit GTA when applied at 1.0 oz/prod/acre and Katana applied at 2.0 oz/prod/acre. Katana resulted in the total elimination of ryegrass and resulted in a fully necrotic canopy (straw cover) within two weeks after application to July 19, 2006 (72 Days after treatment). The development and persistence of necrotic leaf tissue of perennial ryegrass (straw) had the greatest impact on decreasing overall turfgrass quality ratings. No treatment went through the summer without some loss of quality at some point, including the untreated control. Certainty had little or no effect on transition when applied once at the rate of 1.25 oz/prod/acre. Surflan was not effective in ryegrass transition. The tank mix of Transit and nicosulfuron applied at the rate of 0.25 oz/prod./A each, produced an enhanced transition with nominal quality. In similar fashion, Monument applied at 0.35 oz./A produced an enhanced transition with nominal quality. A rates used in this test, other treatments had either too slow of a transition or had poor and extended low quality turf scores from rapid development of dead ryegrass (straw) and subsequent slow bermudagrass re-establishment. The UTC turf maintained a high percentage of living green ryegrass into the summer and 20% live ryegrass on August 8, 2006 which is roughly six weeks before the next overseeding.

For pre-emergence control of Poa annua (PA), Dimension as the EC and 270 G (granular) formulations were applied either as single applications at 6 and 8 weeks before fall overseeding, followed by sequential applications of Barricade. Barricade was also applied 6 and 8 weeks before overseeding. The plots were overseeded on October 2, 2006 with a Citation III perennial ryegrass blend at the rate of 625 lbs PLS/A. When overseeded with perennial ryegrass: Both pre-emerge treatments of the 270G formulation, and Barricade applied at 0.77 lbs AI/A six weeks before overseed (6WB0S) had moderate to severe stunting. Both Dimension treatments (6 and 8 weeks BOS) had no apparent loss of vigor, and were equal in vigor with that of the non-treated turf. By mid December , the 270G treatments produced the least amount of ryegrass cover. Also on October 18, there was a slight reduction in ryegrass cover for Dimension and Barricade treated turfs. The single application treatments of Dimension produced slight/moderate percent weed control in February and March, which declined rapidly by the end of March. On March 15, Dimension applied at 32 ounces/product/acre at 6 and 8WBOS had a season maximum of 43%, and 20% weed control, respectively. Barricade applied at 0.77 lbs. product/A had the highest amounts of PA control realized in this test. The pre/post application of Barricade (alone) produced percent weed control values statistically similar to that of the single pre-emergence application of Barricade alone at either 6 or 8WBOS. The 270G treatments produced much higher levels of percent (PA) control than the liquid formulation on all three dates. In non-overseeded turf: Liquid Dimension treatments showed NO control whatsoever at 8WBOS. At 6WBOS, 24% PA weed control was the highest control achieved early on at the November 2 evaluation. Barricade, when applied once as a pre-emergence, had good to moderate percent PA weed control, which declined after December (45% in January) at the 6WBOS timing. The 270G treatments had very good initial weed control (as it did on the overseeded plots) with 93–97% weed control on November 2, 89% - 91% on November 17, and 71-80% weed control on December 7. The affect of overseed alone on suppression of PA was 72%, 60%, and 52% (16 Feb, 15 Mar, and 26 Mar).

Kentucky bluegrass (Poa pratensis L.), cv. Nu Star was studied in a greenhouse to evaluate its growth responses in terms of shoot length and dry weight under NaCl (sodium chloride) salinity and different levels of Trinexapac-ethyl( primo Max). Plants were grown hydroponically under control and one level of salinity [EC (electrical conductivity) of 5 dS/m] and three levels of primo Max (0.3, 0.6, and 0.9 oz/1000 ft²), using Hoagland solution No. 1. Plant shoots (clippings) were harvested weekly, oven dried at 60 oC, and dry weights recorded. At each harvest, shoot length was measured and recorded, percent visual canopy green cover was also estimated. The results show that shoot length and shoot dry weight (DW) of Kentucky bluegrass significantly decreased with both salinity and primo treatments, although the differences in shoot length and shoot DW were not significant between primo treatments at 0.6 and 0.9 oz/1000 ft² application rates. The green coverage of the turf canopy decreased under salinity stress, and the reduction of green canopy coverage by salinity was more pronounced when turf was treated by primo, suggesting that primo significantly reduced the salt tolerance of Kentucky bluegrass. The above results were observed for both cumulative as well as the weekly growth responses.

Pessarakli, Mohammed; Kopec, David M.; Berry, Sarah C (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2004-02)

Zoysiagrass (Zoysia spp.), cv. El Toro was used in this experiment to evaluate its shoot growth in terms of length and dry weight under control and different levels of Bio-Turf-Pro applications in a pot study. Four treatments [Control (no Bio-Turf-Pro), 8 Fl Oz/Gal (½ the recommended rate) per 1000 ft², 16 Fl Oz/Gal (recommended rate) per 1000 ft², and 32 Fl Oz/Gal (twice the recommended rate) per 1000 ft² of Bio-Turf-Pro], and six replications of each treatment were used in a RCB design in this investigation. Plants were allowed to grow under the above treatment conditions for eight weeks. Plant shoots (clippings) were harvested bi-weekly for the evaluation of the dry-matter production. At each harvest, shoot lengths were measured and recorded and the visual growth was also evaluated before the harvest was made. The harvested plant materials were oven dried at 60o C and dry weights were measured and recorded. The shoot growth (length) was stimulated under any levels of Bio-Turf- Pro application rates compared with the control. Among the treatment rates, the 16 Fl Oz/Gal (the recommended rate) per 1000 ft²] numerically stimulated the shoot length the most. However in most cases, there was not statistically significant differences detected among the 8 (½ the recommended rate) per 1000 ft², 16 Fl Oz/Gal (the recommended rate) per 1000 ft²] and the 32 Fl Oz/Gal (twice the recommended rate) per 1000 ft²] application rates of the compound on the shoot length of the grass. The shoot (clippings) dry weights of the plants followed essentially the same pattern as the shoot lengths. The visual evaluation of the grass supported the measured parameters.

Pessarakli, Mohammed; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2009-02)

This study was conducted in a greenhouse, using hydroponics system, to compare growth responses of three cool-season turfgrass species, Creeping bentgrass (Agrostis stolonifera), Rough bluegrass (Poa trivialis), and Perennial ryegrass (Lolium sperenne) in terms of shoot and root lengths and dry matter (DM), and percent canopy green cover (%CGC) under salinity and drought stresses. Grasses were grown in Hoagland solution for 90 days prior to initiation of salinity or drought stresses. Then, 24 meq NaCl/L culture solution/day were added for each -0.1 MPa OP of salinity stress, or 75 and 119 g of PEG/L were added for -0.2 and -0.4 MPa OP of drought stress treatments, respectively. The treatments included control, -0.2 and -0.4 MPa OP salinity, -0.2 and -0.4 MPa OP drought stress. Four replications of each treatment were used in a RCB design experiment. During the stress period, grass shoots were clipped weekly for DM production, shoot and root lengths were measured, and %CGC was evaluated. The weekly clippings and the roots at the last harvest were oven dried at 60° C and DM weights were recorded. All 3 grass species were more severely affected by drought than salinity. Bluegrass was the most and bentgrass the least severely affected by either drought or salinity stress.

TGR (paclobutrazole) was applied to both overseeded and non-overseeded turfs in repeat monthly applications at either 8.0 oz or 12.0 oz product/1000 ft² rates. Applications were made in repeat monthly intervals to apply either three, four or five repeat applications beginning in December 2007, and ending in April 2008. When applied as a post emergent PGR material, TGR caused only a slight decrease in turfgrass color and quality of overseeded turfs in March at the high (and repeated) rate of 12.0 oz/product/acre. This effect was short lived, as overseeded turfs for the remainder of the season maintained fully acceptable color and quality through the spring transition period. Tenacity turfs always had quality scores of 6.0 or higher throughout the test. Seed head suppression was realized from TGR, with greater head suppression at the 12.0 oz rate than that of the 8.0 oz rate. Bermudagrass transition among TGR treated turfs was not different from that of the untreated controls, whether the turfs were overseeded or not. On 20 June 2008, percent bermudagrass plot cover ranged from 29-58% for TGR treated turfs, 40% for Tenacity, while the overseeded UTC had 35%, on average. The percent bermudagrass increased quickly after a 2.0 lb. /N /M application on June 20, to 68% to 90% bermudagrass cover for TGR treated turfs (UTC = 83%). After a scalping event (from 1.25 inches to 0.50 inches) performed on July 1, percent bermudagrass decreased temporarily (from bermudagrass removal), but rebounded within 15 days to yield 96% to 99% bermudagrass cover by the close of the test on 31 July, 2008. Like wise, Tenacity alone did not inhibit transition, as Tenacity treated turfs had bermudagrass cover slightly greater than that of the overseeded controls.

Overseeding bermudagrass turf with perennial ryegrass is essentially a standard practice in south western turfgrass maintenance. This practice complicates (and often negates) the pre-emergence control of Poa annua (PA) which germinates within the overseeding window. Outplay (mesotrione) was applies as pre , post and pre+post applications to control PA in golf turf (overseed on October 2, 2006). Outplay was applied with Trimmit as a post emergence treatment. Barricade and Barricade + Monument were applied post emergence. On non overseeded turf: The greatest amount of (PA) weed control was achieved by the treatment of Barricade 16 ounce/product/acre (8WBOS) and Monument 16 gm (2WBOS) (Table 3). This treatment had no PA initially (2 November) 93% control on 17 November, and 7 December, 90% control on 4 January, dropping to 77% control by 16 February. Outplay applied pre-emergence as a sole treatment had little or no affect on PA, providing essentially no control. This was even true for the high rate of 16 ounces of product, applied 1 week before overseeding. Outplay applied both pre/post at eight ounces also had little effect on PA. The same was true for Outplay applied as two post emergence treatments [( 8 + 8 ) or (16 + 16) ounce rates] (Table 3). Prograss had a maximum weed control of 50% on January 4, sixteen days after its repeat application of 64 ounce. The post emergence tank mix of Outplay and Trimmit, followed by Trimmit alone had a maximum of 50% (PA) weed control on January 4, which declined afterwards. Overseeded Turf: Barricade and Barricade plus Monument had good control initially (94% 16 February), noting that the addition of Monument increased percent weed control by 10% in March (Table 8). Outplay applied alone as a pre-emergence product, had minimal control, with the high rate of 16 ounces applied 1 week before overseeding providing nominal weed control (65%, 41%, 58%) on 16 February, 15 March, 26 March, respectively. Outplay applied as a post emergence treatment only, exhibited good to moderate weed control, with the 16 and 16 ounce repeat treatments having better weed control than the 8 ounce plus 8 ounce treatments (applied 8 weeks and 12 weeks after overseeding, respectively). The 16 and 16 ounce treatment had 100%, 82% and 78% weed control on 16 February, 15 March, and 26 March, respectively (Table 8). Prograss applied twice as a post emergence provided similar levels of PA control (100%, 85%, 89%) on those same dates, respectively. Finally, when Outplay was applied as a post emergence treatment with Trimmit, weed control was good to moderate, providing 88%, 67%, and 78% weed control on overseeded turfs on 16 February, 15 March, and 26 March, respectively (Table 8). The affect of overseeding itself based on NTC means of overseeding and nonoverseed turfs (no herbicides) showed that overseeding alone suppressed PA by 93% on 16 February, 91% on 15 March and 59% on 26 March.

Pessarakli, Mohammed; Marcum, K. B.; Kopec, David M. (College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001-09)

Fourteen (14) Arizona accessions and 7 Colorado accessions of Saltgrass (Distichlis spicata), collected from Arizona and Colorado and 1 Bermudagrass (Cynodon dactylon), cultivar Midiron (check), were studied in a greenhouse to evaluate their growth responses in terms of shoot dry weights and percentage of visual green under drought stress conditions. Plants were grown under normal (daily watering and weekly fertilizer application) for one year for complete establishment. Then, the plants were deprived from water for four months (January 5, 2001 - May 5, 2001). Plant clippings were harvested weekly, oven dried at 60 °C, and the dry weights were recorded. At each harvest, percentage of green cover were also estimated and recorded. After the last harvest, plants were re-watered to assess and compare the percent of recovery. Overall, the results (both shoot dry weights and the percent of the visual green) show that the A138 and A137 (Arizona accessions) were the best accessions and the C66 (Colorado accession) was the worst. Both the shoot dry weights and the percent of visual green cover decreased as the drought period progressed. In general, most of the saltgrass accessions were more tolerant to drought stress than the bermudagrass.

Spring transition (from ryegrass to bermudagrass) has been problematic for the last 20 years based on, in part, improved heat tolerance and lower growing cultivars of perennial ryegrass. Annual ryegrass is used sparingly for commercial properties and for home owners in southern Arizona. Hybrid ryegrass (cross between perennial and annual ryegrass) has been manufactured by seed companies in an effort to improve the transition of a grass used specifically for overseeding, with improved turf grass attributes over those of annual ryegrass. A field test was conducted to evaluate several hybrid ryegrasses, two improved annual ryegrasses, and Gulf annual ryegrass under homeowner conditions. The true annuals produced the quickest amount of ground cover in the shortest period of time. By early December, all plots had 98% or more cover, with FH having 95% cover. Transend, Transport and 041 Lh had consistently high quality scores throughout most of the 8 month test, with Transport and 04 1 LH scoring for fair turfgrass quality into mid June. Sprint annual ryegrass had excellent turfgrass quality scores in November and December, however, scores declined substantially in April and afterwards. After emergence and into early December, Transport and 041LH clearly had the darkest turf coloration, with 041LH producing a turf with a color intensity typical of medium green perennial ryegrass. Gulf and FH were noticeably lighter in color. Gulf, Sprint and Transcend developed ring/patch type disease symptoms in early February 2007, while others did not. "Stemminess" ratings in late spring (a time at which annual ryegrass is typically pronouncedly so) showed that FH intermediate and Gulf produced the most "stemmy" turfs, followed by Sprint annual. Transport and 041LH showed hardly any seed head culm development, with Transcend being intermediate. Interestingly, not all the entries which generally had the highest numerical rankings for density, texture, uniformity and overall turfgrass quality, had the highest percent plot living overseed during transition. Entry 041LH had 30% overseed, 46% bermuda, and 24% straw. Transcend had 16% overseed, 25% straw and59% straw on June 12. Transport had the highest retention of green overseed (72%), with 23% bermuda and 5% bare ground or straw plot cover. Sprint had 19% overseed, 20% live bermudagrass, and 61% bare straw plot cover, more so than that of Gulf. Final quality scores showed that 041LH and Transport had the best quality mean rank values, with all others having low quality scores on 12 June just prior to scalping to fully reconstitute the underlying Tifway bermudagrass. This shows vast improvements in turfgrass performance for INTERMEDIATES, which previously (and again) show near full acceptability in most turfgrass attributes, and now show enhanced color. Likewise, improvements in strict annual types show improved turf quality (Sprint) over Gulf.

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